Selective printer power supply arrangement

ABSTRACT

In order to do away with the need for bulky smoothing capacitors in a power pack for a serial printer an arrangement of switching devices is provided together with a programming means which ensures that acceleration of the printer&#39;&#39;s printhead occurs between a peak of one half-cycle of the rectified unsmoothed supply and the following zero, coasting and printing occur during the next half-cycle (zero-to-zero), and deceleration occurs between the zero and peak of the third half-cycle.

United States Patent [191 Mason, deceased et al.

[ Oct. 21, 1975 SELECTIVE PRINTER POWER SUPPLY ARRANGEMENT [75] Inventors: Frederick Percival Mason, deceased,

late of Burgess Hill, England, by Margaret Maud Mason, executrix; Brian Michael Patience, Eastbourne, England [73] Assignee: International Standard Electric Corporation, New York, N.Y.

[22] Filed: Nov. 13, 1974 211 Appl. No.: 523,356

[52] U.S. Cl. 321/47; 318/227; 318/387;

318/392 [51] Int. Cl. H02M 7/06 [58] Field of Search 178/19, 20, 23 R, 66-68,

Kelemen et a1 318/227 Scheuer et al. 318/227 X Primary Examiner-William M. Shoop Attorney, Agent, or Firm-A. Donald Stolzy [57] ABSTRACT [56] References Cited UNITED STATES PATENTS 3 Claims, 4 Drawing Figures 3,639,818 2/1972 Wiart 318/227 X l l I l l l l l I01 I I l "5 I16 I m I 102 HWTT 108 I T T ll I l US. Patent Oct. 21, 1975 Sheet 1 of 4 3,914,682

U.S. Patent Oct. 21, 1975 Sheet 2 of4 3,914,682

F|G.2 ABCD ACCELERATION 0 c5 ER (ON OFCARRIAGE QECA RRQEE PRINTING OF CHARACTER ONE OPERATING CYCLE DECEL.

om: CHARACTER Q PITCH ACC.

o TIME U.S. Patent Oct. 21, 1975 Sheet3of4 3,914,682

FIG.3

SELEKITHVE PRINTER POWER SUPPLY ARRANGEMENT This invention relates to an arrangement for supplying power to a serial selective printer, such as a teleprinter.

With present-day electronic techniques most of the components of electric control and switching arrangements have become very small and one of the components which has not, and is not likely to become small is the storage or smoothing capacitor used in the conversion of alternating current to direct current. Therefore, arrangements which avoid the need for smoothing rectified alternating current are desirable. The arrangement described below is such a one.

According to the present invention there is provided a serial selective printer power supply arrangement comprising: rectification means for providing unsmoothed unidirectional currents from an alternating current supply; a set of switches for permitting said unidirectional currents selectively to energize, in a set pattern, windings of a print head traversing motor; a further set of switches permitting said unidirectional currents selectively to energize motors in the print head which effect the actual printing of a character; and control circuit means including a store for character code signals, whose characters are to be printed, sensing means for detecting the coincidence of a peak of a halfcycle of unidirectional current and a presence of a character code signal in the store, and a store holding an energization program which is enabled by said sensing means when a coincidence as above is detected and causes the print head to be accelerated between the sensed peak and the following zero, to be held in constant motion during the next half-cycle, during which time a character corresponding to the stored character code signal is printed, and to be brought to rest between the zero and the peak of the next half-cycle.

Embodiments of the invention are described below with reference to the accompanying diagrams, of which:

FIG. 1 shows-the basic switching arrangement of one embodiment for supplying a traversing motor and printhead energization in a selective printer from a source of alternating current;

F 16. 2 shows the relation between a printing operation and one complete cycle of alternating current from the source in FIG. 1;

FIG. 3 shows a logic diagram of a control arrangement for correctly actuating the supply arrangement of FIG. 1; and

FIG. 1 shows the basic switching arrangement of a second embodiment.

Refer to FIG. 1.

A source of alternating current is applied at terminals 1111 and NZ to the inputs of a full-wave bridge rectifier 1113, from the outputs of which a unidirectional but unsmoothed current can be conveyed by the current busbars 1114i and 1115 to apparatus connected between them. Between the busbars are connected the windings of a traverse motor and their associated switches 106, and the windings of the motors of a stylus printhead, and their associated switches, 107. The switches are indicated here as transistors, merely for the sake of simplicity. They can, in fact, be any suitable type of switch, whether electromagnetic, electrostrictive, or semiconductive.

The traverse motor, which is the motor which causes a printhead to move from one edge of a page towards the other, has two windings, both centre-tapped, as at 10%.

The ends of the windings are each connected, at 109, 110, Ill and 112 respectively to one end of the individually associated switches 113, 114, 115, and 116, the other ends of which are commoned and connected to busbar 104, while the centre-taps of the windings are connected to busbar 105. In a similar way, at 117 one end of each of the stylus motor windings 118, 119 120, 121 is connected to one end of an individually associated switch 123, 124 125, 126, and the other ends of the switches are connected in common to the busbar 104 while the other ends of the windings are connected in common to the busbar 105.

It should be realised that we have employed the word motor in its broad sense of that which imparts motion, and it is not restricted to a rotating motor. The traverse motor may well be of rotating form, but the stylus motors are likely to be solenoids.

Consider first the print head. To form a character for printing, various of the styli must be energized in the correct pattern. The switches associated with the styli to be energized will thus be controlled by some device which in response to any input character signal produces the correct corresponding pattern of energization.

Consider the traverse motor. Assuming the motor and printhead to be at rest initially they must be accelerated to a required speed, maintained at that speed for a definite length of time, and then decelerated again to rest. With the unsmoothed unidirectional current available from the busbars accelerated is to take place during the second half of a half-cycle of current, steady motion and energization of the stylus motors is to take place in the following half-cycle and deceleration is to take place in the first half of the next half-cycle.

FIG. 2 shows this relationship. In the upper part of the figure, which shows an unrectified waveform, acceleration occurs between the peak of a half-cycle and the following zero, the acceleration actually ceasing before the zero is reached.

During the next following half-cycle, from a point slightly after the zero, through the peak, and to a point just before the following zero, the traverse motor is maintained at constant speed, and the stylus motors are energized as required to provide the printed character.

Finally the motor is decelerated to rest between the zero preceding the next following half-cycle and the peak of that half-cycle.

The traverse motor moves by the energization of individual windings in a succession of patterns, this being accomplished by the closing of the corresponding switches. For instance the succession of patterns may be: close switches 13 and 15; open 15 and close 16; open 13 and close 1 1; open 16 and close 15. This succession is then repeated, as often as is necessary. When started from rest the motor will accelerate by these repetitions to its full speed; after full speed has been reached it will be maintained by the continuance of these repetitions; during the deceleration phase the same repetitions are used but they occur at such, times as to retard the motor rather than assist in maintaining its motion. An arrangement to perform all these actions is described below with reference to FIG. 3.

The alternating current, or the corresponding voltage on busbar 104 is sensed by an interrogating device 301 over lead 302. When a peak current or voltage is sensed the interrogator is triggered to test the condition of an input character signal queueing store 303 over a test path (which may actually comprise a plurality of leads) 304. The store 303 receives the character signals which it stores over an input signal path 305 (which again may be a plurality of leads). If there is a predetermined minimum number of character signals present in the store 304, then the test will prove successful and the interrogator will send an enabling signal over lead 306 to AND-gate 307. The other input to AND-gate 307, over lead 308, is the alternating current or voltage from busbar 104, and the coincidence of the two signals opens the gate and sets toggle 309 to its B side. From the B-side an enabling signal is applied over lead 310 to one input of AND-gate 311 and stays applied until the toggle is cleared. The other input of AND-gate 311 is connected over lead 312 to a clock 313 which gives out a regular train of pulses. Each pulse occurring in conjunction with the enabling signal from toggle 309 opens gate 311 and causes a cyclically accessed store 314 to provide, on its output leads 315, 316, 317 and 318, a different pattern of energization which pattern is applied to the switches 113, 114, 115, and 116. One way of realizing the store 314 is with a read-only memory having n stored energization patterns, and a n state cyclic distributor, each state of the distributor giving access to an individually associated stored pattern, and

.the distributor being driven through its cycle by the leads 322 which can be selectively energized simultaneously in accordance with the character signal applied to its input leads. If the printhead is of the type in which successive columns of dots in a rectangular array are printed in succession, then the converter will have 7 output leads which can be energized at any one or more of 5 successive instants so timed that as the stylus head moves at constant velocity past the printing web dots are made in any one or more of five columns spaced apart at equal intervals. Converters of either type are well-known and the details of them are not described here.

The printing of the character takes place during the half-cycle in which the printhead is moving at constant speed. When the printing is accomplished and the halfcycle has reached zero the signal pattern generated from store 314 is now displaced in phase with respect to the preceding patterns, the windings of the traverse motor thus being so energized that they oppose the motion of the motor, and so slow it until by the peak of the following half-cycle the motor and printhead are halted. At this moment the store 314 sends a signal over lead 323 to the A-side of toggle 309, restoring it to its rest condition and cutting off the train of pulses from clock 313 to store 314.

The circuit is now ready to repeat its action for the next character when available.

FIG. 1 shows an arrangement using a full-wave bridge rectifier. In this arrangement any half-cycle of the input supply can be the start of a sequence accelerate coast-and-print decelerate. In FIG. 4 is shown a different arrangement. The current source at terminals 401 and 402 feeds through two half-wave rectifiers 403a and 403b to a positive busbar 404a or a negative busbar 404b, and returns by neutral busbar 405. The accelerate and decelerate switches 413, 414, 415, and 416 (numbered to agree with corresponding switches 113, 114, 115, and 116 in FIG. 1) are connected through winding 409, 410, 411 and 412 between busbars 404a and 405. The print switches 422, 423, 424 and 425 (numbered to agree with corresponding switches 123, 124, and 126 of FIG. 1) are connected, through winding 418, 419, 420 and 421, be tween busbars 404k and 405. Additionally a set of switches 470, 471, 472 and 473 is provided, connected between busbars 404k and 405 through windings 409, 410, 41 l, and 412; these provide the coast or constant motion drive currents to the traverse motor during the printing period. In this arrangement a sequence accelerate coast-and-print decelerate can only begin in a-half-cycle in which terminal 401 is positive with respect to terminal 402.

We claim:

1. A serial selective printer power supply arrangement comprising rectification means for providing unsmoothed unidirectional currents from an alternating current supply, a set of switches for permitting said unidirectional currents selectively to energize, in a set pattern, windings of a print head traversing motor, a further set of switches permitting said unidirectional currents selectively to energize motors in the print head which effect the actual printing of a character and control circuit means including a store for character code signals, whose characters are to be printed, sensing means for detecting the coincidence of a peak of a halfcycle of unidirectional current and a presence of a character code signal in the store, and a store holding an energization program which is enabled by said sensing means when a coincidence as above is detected and causes the print head to be accelerated between the sensed peak and the following zero, to be held in constant motion during the next half-cycle, during which time a character corresponding to the stored character code signal is printed, and to be brought to rest between the zero and the peak of the next half-cycle.

2. An arrangement as in claim 1 in which the alternating current is full-wave rectified and supplies currents to two busbars between which both sets of switches are connected.

3. An arrangement as in claim 1 in which the alternating current is half-wave rectified and supplies currents to three busbars: a first neutral busbar, a second busbar having one polarity with respect to the neutral, and a third busbar having a polarity opposite to that of the first busbar with respect to the neutral, in which the set of switches permitting currents to energize the print head traverse motor windings has two parts, the first part connected between the second and first busbars, for acceleration and deceleration, and the second part connected between the third and first busbars, for constant motion, and in which the further set of switches permitting current to energize the printing motors is connected between the third and first busbars. 

1. A serial selective printer power supply arrangement comprising rectification means for providing unsmoothed unidirectional currents from an alternating current supply, a set of switches for permitting said unidirectional currents selectively to energize, in a set pattern, windings of a print head traversing motor, a further set of switches permitting said unidirectional currents selectively to energize motors in the print head which effect the actual printing of a character and control circuit means including a store for character code signals, whose characters are to be printed, sensing means for detecting the coincidence of a peak of a half-cycle of unidirectional current and a presence of a character code signal in the store, and a store holding an energization program which is enabled by said sensing means when a coincidence as above is detected and causes the print head to be accelerated between the sensed peak and the following zero, to be held in constant motion during the next half-cycle, during which time a character corresponding to the stored character code signal is printed, and to be brought to rest between the zero and the peak of the next half-cycle.
 2. An arrangement as in claim 1 in which the alternating current is full-wave rectified and supplies currents to two busbars between which both sets of switches are connected.
 3. An arrangement as in claim 1 in which the alternating current is half-wave rectified and supplies currents to three busbars: a first neutral busbar, a second busbar having one polarity with respect to the neutral, and a third busbar having a polarity opposite to that of the first busbar with respect to the neutral, in which the set of switches permitting currents to energize the print head traverse motor windings has two parts, the first part connected between the second and first busbars, for acceleration and deceleration, and the second part connected between the third and first busbars, for constant motion, and in which the further set of switches permitting current to energize the printing motors is connected between the third and first busbars. 